Myology of the shoulder region

Question 1

Origin of latissimus dorsi?

Answer 1

Thoracolumbar fascia
Spinous processes T7-T12
All lumbar and sacral vertebrae and their interspinous and supraspinous ligaments
Posterior part of the outer lip of iliac crest
Lower 4 ribs
Inferior angle of scapula

Question 2

Insertion of latissimus dorsi?

Answer 2

Via long flat tendon which twists 180 degrees into the floor of the intertubercular groove of humerus

Question 3

Action of latissimus dorsi?

Answer 3

Adducts, medially rotates, and extends the arm at the shoulder joint

Question 4

Innervation of latissimus dorsi?

Answer 4

Thoracodorsal nerve (C6-C8)

Question 5

Origin of rhomboids?

Answer 5

Both attach to spinous processes and covering ligaments
Major - T2-T5
Minor - C7-T1

Question 6

Insertion of rhomboids?

Answer 6

Medial border of the scapula

Question 7

Action of rhomboids?

Answer 7

Elevate, retract, and medially rotate the pectoral girdle

Question 8

Innervation of rhomboids?

Answer 8

Dorsal scapular nerve (C5)

Question 9

Origin of serratus anterior?

Answer 9

Outer surfaces of upper 8-9 ribs and intercostal fascia

Question 10

Insertion of serratus anterior?

Answer 10

Costal surface of the medial border of scapula

Question 11

Action of serratus anterior?

Answer 11

Protracts and laterally rotates the scapula

Question 12

Innervation of serratus anterior?

Answer 12

Long thoracic nerve (C5-C7)

Question 13

Origin of pectoralis major?

Answer 13

Medial half of anterior border of the clavicle, anterior surface of the sternum, anterior surface of the 6 upper costal cartilages and 6th rib

Question 14

Insertion of pectoralis major?

Answer 14

Via laminated tendon into lateral ridge of intertubercular groove of humerus

Question 15

Action of pectoralis major?

Answer 15

Flexes (to 90 degrees), medially rotates, and adducts arm at the shoulder

From full flexion, lower fibres also extends the shoulder to midline against resistance

Question 16

Innervation of pectoralis major?

Answer 16

Medial (C8-T1) and lateral (C5-C7) pectoral nerves

Question 17

Origin of pectoralis minor?

Answer 17

Coracoid process of the scapula

Question 18

Insertion of pectoralis minor?

Answer 18

Outer surface of 3rd, 4th, and 5th rib and intercostal fascia

Question 19

Action of pectoralis minor?

Answer 19

Protracts and medially rotates the scapula

Question 20

Innervation of pectoralis minor?

Answer 20

Medial and lateral pectoral nerves (C6-C8)

Question 21

Origin of the deltoid?

Answer 21

Anterior fibres: Lateral 1/3 of anterior border of clavicle
Middle fibres: Outer margin of the acromion
Posterior fibres: Lower border of the spine of the scapula

Question 22

Insertion of the deltoid?

Answer 22

Deltoid tuberosity of the humerus

Question 23

Action of the deltoid?

Answer 23

Anterior fibres: flexes, abducts, and medially rotates the shoulder
Middle fibres: abducts the shoulder
Posterior fibres: extends, abducts, and laterally rotates the shoulder

Question 24

Innervation of the deltoid?

Answer 24

Axillary nerve (C5-C6)

Question 25

Origin of teres major?

Answer 25

Lower third of the lateral border and inferior angle of scapula

Question 26

Insertion of teres major?

Answer 26

Medial lip of intertubercular groove of humerus

Question 27

Action of teres major?

Answer 27

Adducts and medially rotates the shoulder

Question 28

Innervation of teres major?

Answer 28

Lower subscapular nerve (C6-C7)